Blender Cycle too much noise
Normally, you'd have to increase the sample count (4x to halve the noise...)

At the noise level you show in your image, and if you are using Blender 2.79, you can try to use the noise reduction: in the Render options, switch 'feature set' to 'experimental', then in the 'render layers' tab activate the 'Denoising' option.
Denoising will add a bit to your render time (but less than increasing the sample count), and can lead to some loss of fine detail. It's up to you to decide if the detail loss is a problem.

I don't think they will be very useful for your scene here, but some other options that can reduce fireflies are:
-  in the render tab, under 'Light paths': (slightly) increase 'filter glossy'
- in the render tab, under 'sampling': set the 'clamp' options to a value higher than zero (the higher, the less effect, but there's no upper bound afaik)